Universal joint

ABSTRACT

A universal joint having a cross-member journal or trunnion with a lubrication chamber includes a combination of a thrust washer and lubrication baffle press fit into the lubrication chamber. The thrust washer and lubrication baffle incorporate one or more lubrication grooves, facilitating the flow of lubricant between the surfaces of the cross-member and bearing cap. Elastomeric properties of the thrust washer eliminate the need for grinding of the journal surfaces to desired tolerances, while incorporation of lubrication grooves into the thrust washer surface eliminates the need for pressing of lubrication grooves directly into the journal ends prior to hardening or heat treating.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a division of and claims priority to U.S.patent application Ser. No. 10/760,053, filed Jan. 16, 2004, which iscurrently allowed, and which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to universal joints havingcross-member journals provided with internal lubrication channels whichopen at the ends of the journals to provide for replenishment oflubricant in bearing cups within which the journals are pivotallysupported in respective yoke members, and in particular, to such auniversal joint having a washer and lubrication baffle press-fit withinan enlarged end portion of the lubrication channel.

2. Related Art

Typically, within the cross-members or trunnions of a universal joint,the lubrication channels intersect at a central location, adjacent anexternal lubrication fitting, whereby lubricant can be introduced to theuniversal joint when required, as shown in U.S. Pat. No. 4,103,512 toMcElwain, et al. The lubricant introduced to the central location of theuniversal joint typically flows radially outward towards the ends of thecross-member journals through the individual lubrication channels.During operation, the rotational movement of the universal joint aboutan axis perpendicular to the cross-members generates centrifugal forceswhich assists the outward flow of lubricant to the bearing cups.

When rotation of the universal joint is stopped, one or more of thejournals may be disposed in a vertically upward orientation, such thatthe force of gravity acts to draw lubricant back downward from thebearing cups and into the lubrication channels. Upon resumption ofrotational motion, the associated bearing caps may be left with littleor no lubricant, resulting in higher frictional forces and undesiredwear.

In addition to the use of lubricant to reduce frictional wear betweenthe cross-member ends and bearing caps, manufacturers often dispose athrust washer as a buffer between the inner surface of the bearing capand the cross-member or trunnion end, such as is shown in U.S. Pat. No.6,264,566 B1 to Nieman et al., or in U.S. Pat. No. 5,813,916 to Lentini,et al. During manufacture, these thrust washers are installed in thebearing caps prior to placement over the cross-member ends, usingspacers to ensure proper location. The corresponding faces of thecross-member ends are ground in a machining operation to ensure adesired tolerance for the thrust washers, and are pressed to provide forone or more lubrication grooves facilitating a flow of lubricant betweenthe thrust washer and the cross-member end.

Accordingly, it is an object of the present invention to overcome thepotential problems associated with lubricant drainage from the proximityof the bearing cups in a universal joint while simultaneouslyeliminating one or more grinding and machining steps from the universaljoint manufacturing process.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present invention provides a universal joint havinga cross-member journal or trunnion with an enlarged lubrication chamberin a lubrication passage thereof which has a combination of a thrustwasher and lubrication baffle press-fit into the lubrication chamber.The combination thrust washer and unitary lubrication baffleincorporates one or more lubrication grooves, facilitating the flow oflubricant between the surfaces of the cross-member and bearing cap.Elastomeric properties of the thrust washer eliminate the need forgrinding of the cross-member ends to desired tolerances, and theincorporation of lubrication grooves into the thrust washer surfaceeliminates the need for pressing of lubrication grooves directly intothe cross-member ends prior to hardening or heat treating.

The foregoing and other objects, features, and advantages of theinvention as well as presently preferred embodiments thereof will becomemore apparent from the reading of the following description inconnection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification:

FIG. 1 is a plan view of a prior art universal joint cross member;

FIG. 2 is a side sectional view of a washer baffle of the presentinvention;

FIG. 3 is a top plan view of the washer baffle of FIG. 2;

FIG. 4 is a bottom plan view of the washer baffle of FIG. 2;

FIG. 5 is an enlargement of a portion of FIG. 4, illustrating avertically aligned rib for press-fit attachment to a cross-member;

FIG. 6 illustrates the placement of a washer baffle of FIG. 2 in a crossmember; and

FIG. 7 is a sectional view of a washer baffle of FIG. 2 press fitted toa cross-member of a universal joint.

Corresponding reference numerals indicate corresponding parts throughoutthe several figures of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description illustrates the invention by way ofexample and not by way of limitation. The description clearly enablesone skilled in the art to make and use the invention, describes severalembodiments, adaptations, variations, alternatives, and uses of theinvention, including what is presently believed to be the best mode ofcarrying out the invention.

Turning to FIG. 1, a conventional Hookes-type universal jointcross-member or trunnion is shown generally at 10. The cross-member 10consists of four equidistantly spaced journals 12 disposed about acentral body 14. A lubricant channel 16 extends axially through eachjournal 12, from a common central point C, to an open-ended lubricationchamber 18 adjacent a radially outward end 20 of each journal 12. At thecentral point C in the central body 14, one or more lubricant accesspassages 22 are provided for the introduction of a lubricant into thelubricant channels 16.

Each lubrication chamber 18 is defined by an enlarged diameter portionof the associated lubrication channel 16 having a generallyfrustoconical radially inner surface 24 receiving the lubricationchannel 16, and cylindrical sidewalls 26. The radially outer end of thelubrication chamber 18 is open, and includes a chamfered peripheral edge28 transitioning between the cylindrical sidewalls 26 and the outwardend 20 of the journal 12.

Turning to FIGS. 2-4, an washer baffle combination of the presentinvention is shown generally at 100. The washer baffle consists of athrust washer portion 102, and an associated baffle portion 104 adaptedfor press-fitting into the lubrication chamber 18 of a universal jointjournal 12. Preferably, the thrust washer portion 102 and the associatedbaffle portion 104 are of a unitary elastomeric construction. Onesuitable material from which the washer baffle combination may be formedusing conventional plastic forming techniques is a nylon elastomeridentified as DuPont 70G33L, and sold under the “Zytel” brand name by E.I. duPont de Nemours & Co. of Wilmington, Del. Those of ordinary skillin the art will recognize that other materials, not limited toelastomers, may be utilized in the construction of the washer bafflecombination 100 of the present invention, provided that necessarytolerances for wear, temperature, and elasticity are met.

As best seen in FIG. 3, the thrust washer portion 102 of the washerbaffle 100 defines an annular surface substantially corresponding to thedimensions of the radially outward end 20 of a journal 12. Disposed inat least the upper surface of the thrust washer portion 102 are aplurality of equidistantly spaced lubricant grooves 106 radiatingoutward from a central axis X of the thrust washer portion 102.Optionally, lubricant grooves 106 may be provided in the lower surfaceof the thrust washer portion 102 as well.

Associated with the thrust washer portion 102, the baffle portion 104 isdisposed concentrically about the central axis X, perpendicular to thelower surface of the thrust washer portion 102. The baffle portion 104is defined by a pair of concentric cylindrical elements 108A and 108Bjoined together by an annular base 110. Cylindrical element 108A definesthe outer cylindrical surface of the baffle portion 104, and ispreferably contiguous with the thrust washer portion 102. As best seenin FIG. 5, the outer surface of the cylindrical element 108A preferablyincludes a plurality of ribs 111 aligned parallel to the central axis X.Each rib 111 is configured to provide a press fit engagement with aninner surface of the journal lubrication chamber 18. Cylindrical element108B defines an inner cylindrical surface of the baffle portion 104, aswell as an open ended axial lubrication delivery passage 112. Theannular base 110 joins the concentric cylindrical elements 108A and 108Bopposite the thrust washer portion 102, defining an annular lubricationretaining volume 114 concentric with the axial lubrication deliverypassage 112. Preferably, the annular base 110 and the cylindricalelement 108B are contiguous with the cylindrical element 108A, however,those of ordinary skill in the art will recognize that the components ofthe washer baffle combination 100 may be formed discretely and joined inconventional manners to provide the equivalent functionality ofcontiguously formed components.

Turning to FIGS. 6 and 7, a press-fit insertion of the thrust washerbaffle combination 100 axially into the lubrication chamber 18 of ajournal 12 is shown. As the thrust washer baffle combination 100 ispress-fitted to the lubrication chamber 18, ribs 111 ensure sufficientengagement between the outer surface of the cylindrical element 108A andthe surfaces of the lubrication chamber 118, retaining the thrust washerbaffle combination therein in a centered position. Upon completeinsertion into the lubrication chamber 118, the underside of the thrustwasher portion 102 is seated against the journal outward end 20, and theaxial lubrication delivery passage 112 is disposed coaxially with thelubrication channel 16 to receive a flow of lubricant there from.Elastomeric properties of the thrust washer portion 102 function toprovide a limited range of tolerance for dimensional variations in thejournal 12 and journal outward end 20, eliminating the need to grindsurfaces of the journal 20 to precise tolerances during a manufacturingprocess.

Once the thrust washer baffle combination 100 is seated in thelubrication chamber 18 of a journal 12, as shown in FIG. 7, a bearingcup 200 is fitted over the thrust washer portion 102 and journal outwardend 20. The bearing cup 200 is retained in a limb 202 of a joint yoke bya snap ring 204. Needle roller bearings 206 are disposed between theouter circumferential surface of the journal 12 and the innercircumferential side wall of the bearing cup 200. An annular seal 208 ina carrier 210 retains lubricant and excludes contaminants from theinside of the bearing cap 200.

During operation of a universal joint including one or more thrustwasher baffle combinations 100 of the present invention, lubricant flowsradially outward from the center of the universal joint cross-member 10along the respective lubrication channels 16, towards the journal outerends 20. When the lubricant flow enters the lubrication chamber 18,outward flow is restricted by the annular base 110 to flow through theopen ended axial lubrication delivery passage 112, where it is deliveredto the journal outer end 20. From the journal outer end 20, thelubricant flow continues between the various surfaces of the thrustwasher portion 102, along the equidistantly spaced lubricant grooves 106to provide lubrication to the needle bearings 206 and other wearsurfaces. When rotational motion of the universal joint stops and theflow of lubricant reverses, such as due to the influence of gravity, avolume of lubricant is retained in the annular volume 114, and preventedfrom returning to the lubricant channel 16, thereby ensuring an adequatelubricant supply at the journal outer end 20 upon a resumption ofrotational motion.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results are obtained. Asvarious changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A universal joint, comprising: at least one journal having an axiallubrication channel therein, said channel having a lubricant chamber atthe outermost end thereof; and a lubricant retention and bearingcomponent comprising an annular thrust washer portion having an uppersurface and a lower surface and having at least one radial lubricationchannel disposed on at least one of the upper surface and the lowersurface, a cylindrical baffle portion perpendicular to, and coaxialwith, said annular thrust washer portion, a cylindrical elementcoaxially disposed within said cylindrical baffle portion, saidcylindrical element open at opposite ends and defining an axiallubrication delivery passage, and an annular base continguously couplingsaid cylindrical baffle portion to said cylindrical element oppositefrom said annular thrust washer portion, said component press fit intosaid lubrication chamber, wherein said cylindrical baffle portion, saidannular base, and said cylindrical element cooperatively define anannular lubrication retaining volume concentric with said axiallubrication delivery passage and an end of said cylindrical elementopens adjacent said annular thrust washer portion.
 2. The universaljoint of claim 1, wherein the at least one radial lubrication channelcomprises a plurality of radial lubrication channels disposed on atleast one of the upper surface and the lower surface of said annularthrust washer portion.
 3. The universal joint of claim 1, furthercomprising a plurality of axially aligned ribs on an outer peripheralsurface of said cylindrical baffle portion.
 4. The universal joint ofclaim 1, wherein said annular thrust washer portion, said cylindricalbaffle portion, said cylindrical element, and said annular base are ofunitary construction.
 5. The universal joint of claim 1, wherein atleast said thrust washer portion is elastomeric.
 6. The universal jointof claim 2, wherein the plurality of radial lubrication channels areradially equidistant.
 7. The universal joint of claim 4, wherein saidannular thrust washer portion, said cylindrical baffle portion, saidcylindrical element and said annular base comprise an elastomericmaterial.
 8. The universal joint of claim 7, wherein the elastomericmaterial comprises nylon.
 9. The universal joint of claim 1, comprisinga frustoconical chamfer disposed between the upper surface of saidannular thrust washer portion and an inner surface of said cylindricalbaffle portion.
 10. The universal joint of claim 1, wherein the end ofsaid cylindrical element which opens adjacent said annular thrust washerportion is disposed below the upper surface of said annular thrustwasher portion.
 11. The universal joint of claim 1, wherein said atleast one journal comprises a plurality of journals.
 12. The universaljoint of claim 11, wherein the plurality of journals comprises fourjournals arranged as a cross-member.
 13. The universal joint of claim 1,further comprising at least one bearing cup which supports said at leastone journal.
 14. The universal joint of claim 13, further comprising atleast one yoke which supports said at least one bearing cup.